1. Field of the Invention
The present invention relates to an ATM switching apparatus and a route setting system in an ATM switching apparatus network having the same. More particularly, the present invention relates to a system for setting S-PVC (Soft-Private Virtual Connection).
2. Description of the Related Art
When a network is operated by a plurality of ATM switching apparatuses, a PVC technique is known as a connection establishing scheme reflecting the intention of an operation administrator in the network. When the network is operated by using the ATM switching apparatuses of an identical vendor, a substitution route which is previously designated by a precut reroute function is used when a fault has occurred. Therefore, the securing of the route can be continued. However, when a network is operated by using the ATM switching apparatuses of a plurality of vendors, the route sometimes cannot be secured because the above function cannot be applied. For such a case, the system to which PNNI (Private Network-Network Interface) operation is applied is known in order to establish a substitution route in case of the fault in the network containing the ATM switching apparatuses of the plurality of vendors for making the network available continuously. In this system, the substitution route can be secured by a connection retry function in the case of the fault using the S-PVC scheme under the PNNI operation network.
However, in the conventional example, it is not possible to designate an optional route in accordance with an instruction of the operation administrator when a connection is established based on the S-PVC scheme under the PNNI operation in which a substitution route is considered. This is because a route is automatically selected based on a route calculation result which has been already obtained in an originated node in the route in issuance of a S-PVC connection establishing instruction in the PNNI network. In this way, when a S-PVC connection is established on the PNNI network, an optimal route is automatically determined using PNNI topology data of the originated node in the route by specifying a destination node. These conventional examples are described in xe2x80x9cPrivate Network-Network Interface Specification Version 1.0xe2x80x9d, (The ATM Forum af-pnni-0055.000, March 1996).
In conjunction with the above description, a system and method for switching a route in case of occurrence of a fault of the ATM switching apparatus is described in Japanese Laid Open Patent Application (JP-A-Heisei 11-355310). In this reference, a substitution route is previously set for a present route between an origination switch and a termination switch. In this case, a band is not secured for the substitution route, and route data is managed. When a fault has occurred on the present route or in a relay switch, the route is switched from the present route to the substitution route and the band is secured. A fault condition on the present route and the substitution route is monitored and a remaining band of the substitution route is monitored. Based on the monitoring result, the route data is updated in the origination switch.
Also, a rerouting method of PVC in an ATM network and a network managing system is disclosed in Japanese Laid Open Patent Application (JP-P2000-59374A). In this reference, a substitution route is previously defined for PVC managed on the network managing system. The substitution route is used when a fault has occurred.
Also, a communication network fault recovering system is disclosed in Japanese Patent No. 2933021. In this reference, a network management system controls a transmission unit through a control line. When a fault has occurred, the network management system releases a band of a path which passes through a fault occurrence portion. Then, the network management system determines a substitution route based on fault recovery classes set for the respective paths.
A method of setting a PVC (permanent virtual circuit) is disclosed in Japanese Laid Open Patent Application (JP-A-Showa 63-82145). In this reference, a PVC is registered or released between packet switching apparatuses of a current use system and a substitution system. For this purpose, data necessary for setting the PVC is inputted from an operator console to a packet switching apparatus connected thereto and is temporality stored therein. A counter packet switching apparatus is determined based on the stored data and a notice packet is produced to have data necessary for the counter packet switching apparatus to set the PVC and is transmitted to the counter packet switching apparatus. The temporality stored data is registered on a retry process registering table in the packet switching apparatus when a reply packet to the notice packet is not received for a predetermined time from the counter packet switching apparatus or when the reply packet indicates a fault end. The retry process registering table is referred to for every time period, and the notice packet is produced again for the data registered on the retry process registering table and is retransmitted to the counter packet switching apparatus. The data registered on the retry process registering table is invalidated when the response packet indicates a normal end, and a retry count of the data registered on the retry process registering table is incremented by one, otherwise. When the retry count exceeds a predetermined value, the fault of the PVC setting is notified from the packet switching apparatus to the operator console.
An object of the present invention is to provide a system in which the connection of an optional route designated by an operation administrator can be established, and the continuation use of a route is guaranteed by a substitution route establishing function by using S-PVC on a PNNI network composed of a plurality of ATM switching apparatuses of vendors, even when a fault has occurred.
In an aspect of the present invention, a method of establishing an S-PVC (soft private virtual connection) connection in a PNNI (private network-network interface) network of a plurality of peer groups, each of which includes at least an ATM (asynchronous transfer mode) switching apparatus as an ATM node, is attained by (a) setting a first identifier and first designated route data associated with the S-PVC channel in each of the plurality of peer groups; by (b) in the ATM node in each of the plurality of peer groups, receiving a call originating request including second designated route data and a second identifier; by (c) comparing the first identifier and the second identifier; by (d) generating a next call originating request containing third designated route data as the second designated route data and the second identifier for a next node based on the first and second designated route data and the second identifier when the first identifier and the second identifier are coincident with each other; by (e) transmitting the next call originating request to the next node; and by (f) repeating the steps (b) to (e) over each of the plurality of peer groups.
Here, the first designated route data may be designated optionally.
Also, each of the first and second identifiers may be an NCCI (network call correlation identifier), or may contain at least one of a destination number CdPN: called party number) and a source number (CgPN: calling party number).
Also, when the one peer group includes the ATM node, the step (a) may includes the steps of (g) determining based on the first designated route data, whether establishment of the S-PVC connection is possible; and (h) setting the first designated route data and the first identifier when it is determined that the establishment of the S-PVC connection is possible. In this case, the first designated route data and the first identifier may be discarded when it is determined that establishment of the S-PVC connection is not possible.
In this case, also, in the step (g), whether the establishment of the S-PVC connection is possible may be determined based on whether the first designated route data is correct from network configuration data. Also, whether establishment of the S-PVC connection is possible may be determined based on whether resources are remained for the S-PVC connection.
Also, when the one peer group includes the ATM node and another ATM node, the step (a) include the step of (i) the ATM node determining based on the first designated route data, whether establishment of the S-PVC connection is possible; (j) the ATM node setting the first designated route data and the first identifier in the ATM node when it is determined that the establishment of the S-PVC connection is possible; and (k) the another ATM node setting the first designated route data and the first identifier in the another ATM node without determining whether the establishment of the S-PVC connection is possible. In this case, the step (i) include the step of determining whether the establishment of the S-PVC connection is possible, based on whether the first designated route data is correct from network configuration data. Also, whether establishment of the S-PVC connection is possible may be determined based on whether resources are remained for the S-PVC connection.
Also, the call originating request may be discarded when it is determined that the first identifier and the second identifier are not coincident with each other.
Also, an automatic routing process may be carried out to determine a route, when it is determined that the first identifier and the second identifier are not coincident with each other.
Also, the first and second designated route data may be designated based on a topology data of the PNNI network. In this case, when the first and second designated route data are described in DTL format, the third designated route data may be generated to have virtual logic hierarchical representation. Also, a portion of the designated route data corresponding to a lowest layer of virtual logic hierarchical representation is deleted, when the call originating request is received.
In another aspect of the present invention, a ATM switching apparatus includes a memory section which stores data indicating whether resources necessary for call origination are not used; a configuration management section which stores topology data indicating virtual hierarchical configuration of a PNNI network to which a peer group belongs, the ATM switching apparatus belonging to the peer group; a first receiving section which receives a call processing request having a first designated DTL (designated transit list) and a first identifier, and stores the first designated DTL and the first identifier in the memory section, when it is determined that establishment of an S-PVC (soft private virtual connection) connection is permitted; a second receiving section which receives a call originating request having a second designated DTL and a second identifier; and a call processing section which generates a new call originating request having a third designated DTL and the second identifier based on the first designated DTL and the second designated DTL, when the first and second identifiers are coincident with each other.
In this case, the first designated DTL may be designated optionally. Also, each of the first and second identifiers may be an NCCI (network call correlation identifier), or may contain at least one of a destination number CdPN: called party number) and a source number (CgPN: calling party number).
Also, the ATM switching apparatus may further include a configuration managing section which refers to the configuration management section to determine whether resources necessary for the establishment of the S-PVC connection are remained. In this case, the first receiving section stores the first designated DTL and the first identifier in the memory section, when it is determined that the resources necessary for the establishment of the S-PVC connection are remained. In this case, the first receiving section may discard the first designated DTL and the first identifier when it is determined that the resources necessary for the establishment of the S-PVC connection are remained. Also, the first receiving section may store the first designated DTL and the first identifier in the memory section when it is determined by another ATM switching apparatus which belongs to same peer group as the ATM switching apparatus that the resources necessary for the establishment of the S-PVC connection are remained.
Also, the ATM switching apparatus may further include an identifier processing section which compares the first identifier and the second identifier. At this time, the call processing section generates the new call originating request based on the first designated DTL and the second designated DTL, when the first and second identifiers are coincident with each other.
Also, the ATM switching apparatus may further include a transmitting section which transmits the new call originating request to a next node. Also, the call processing section may discard the call originating request when it is determined that the first identifier and the second identifier are not coincident with each other. Moreover, the ATM switching apparatus may further include a routing section which carries out an automatic routing process to determine a route, when it is determined that the first identifier and the second identifier are not coincident with each other. In addition, the call processing section deletes a portion of the second designated DTL corresponding to a lowest layer and generates the new call originating request having a third designated DTL based on the first designated DTL and the second designated DTL, when the first and second identifiers are coincident with each other.